KR20220053595A - Control of green macroalgae outbreaks - Google Patents

Abstract

The present invention relates to the control of green macroalgae outbreaks. More specifically, ulva algal blooms can be controlled by live active ingredients contained in seawater of the Mediterranean. We found that seawater from the Mediterranean Sea collected at a particular point (eg, collected at latitude 43°14'N and longitude 5°21'E, or latitude 43°09'N and longitude 5°36'E) , observed that it can promote the death of Ulva lactuka without releasing toxic acid vapors such as, for example, H ₂ S vapors. Taken together, we provide data showing that the seawater contains live microorganisms responsible for promoting the death of Ulva, particularly Ulva lactuka. More precisely, the present inventors provide experimental data indicating that the microorganism that promotes the death of Ulva lactuka and thus the control of Ulva lactuca outbreak is a virus.

Description

Control of green macroalgae outbreaks

The present invention relates to the control of green macroalgae blooms. More specifically, Ulva Lactuka ( Ulva lactuca ) green algae outbreaks can be controlled by live microorganisms, more specifically viruses, contained in seawater collected from the Mediterranean Sea.

Microalgae (or seaweeds) are classified into three main groups based on pigmentation: brown algae, red algae, and green algae. All these microalgae contain high amounts of carbohydrates (up to 60%), medium/high amounts of protein (10% to 47%) and small amounts of lipids (1%) with varying amounts of mineral ash (7% to 38%). to 3%). As available land and freshwater resources decrease, microalgae become an attractive alternative for the production of valuable biomass comparable to terrestrial crops. Cultivation of microalgae under controlled and sustainable cultivation systems is perhaps the future choice method for supplying biomass to meet market development needs.

The high carbohydrate fraction contains various readily soluble polysaccharides such as laminarin, alginate, mannitol or fucoidan for brown algae, starch, mannan and sulfated galactan for red algae, and ulban for green algae. Alginates, one of the major structural polymers of brown algae, provide both stability and flexibility to specimens exposed to running water, and, like other hydrocolloids such as agar and carrageenan, commonly used as thickeners, gelling agents, or emulsifiers. It is one of the industrially relevant carbohydrate compounds found in mass. Various other non-carbohydrate products obtained from seaweed include proteins, lipids, phenols, terpenoids and minerals such as iodine, potassium and phosphorus, which are useful ingredients for both animal and human nutrition.

The interest of microalgae in human nutrition is due to their high mineral concentrations (eg calcium, magnesium and potassium) and glutamic acid, which also makes them useful as taste enhancers. Algae could also help address one of the biggest challenges facing the food industry today. In fact, as seaweed, as opposed to salt, contains small amounts of sodium, it may serve as an alternative to prevent the health risks associated with excessive sodium chloride intake. Microalgae are also a source of active ingredients that are being mainly explored today to manufacture more and more pharmaceuticals. The gelling properties of sulfated polysaccharides are well known and their therapeutic applications are under development. Microalgal polysaccharides, pigments, proteins, amino acids and phenolic compounds are potential functional food ingredients for maintaining health and preventing chronic diseases and have more and more potential uses in the pharmaceutical industry.

In contrast to microalgae, which are of increasing economic interest every year, macroalgae remain a risk, particularly to the marine environment and to human and animal health. Indeed, macroalgae outbreaks damage marine ecosystems and negatively affect local tourism. This is particularly the case with Ulva Lactuka Outbreak.

Ulva lactuka is a macroalgae belonging to the phylum Chlorophyta , first described by Linnaeus in the Baltic Sea in the 18th century. Ulva lactuka algae consist of a double-layered cell structure, and their fronds generally have a flat bladed appearance. It can grow both as a free-floating organ or as a fixed organ such as a rock. Ulva lactuka algae have the ability to reproduce in two ways, one is sexual and the other is due to frond fragmentation rarely observed in macroalgae. Both of these methods provide the ability to rapidly multiply by covering the water surface, reducing the biodiversity of other algal species. Ulva lactuka is a polymorphic species with respect to water salinity or degree of symbiosis with bacteria.

Ulva lactuka mainly invades beaches, and its biodegradation can produce toxic acid vapors (mainly H ₂ S) which induce the biodegradation of Ulva lactuka and possibly the death of animals due to humans (Bretagne, western France, 2009) Horses have been reported to have died on shore).

The first Ulva Lactuka outbreak to be described was in Belfast (Northern Ireland) at the end of the 19th century. Ulva lactuca outbreaks have been well studied in Laguna, Venice since the 1930s, and unexplained declines have been observed since the 1990s. Since the 1980s, Ulva-lactuca outbreaks have been observed worldwide, from Galicia (Spain) to Tokyo Bay (Japan), including the coast of America and Australia. However, the world's largest event so far remains as algae observed in the Yellow Sea for 10 consecutive years since 2007, covering 10% of its surface. In Europe, the largest Ulva Lactuka outbreak is off the north coast of Brittany. Today, it has been acknowledged that the Ulva-lactuca outbreak is primarily a result of human activity, especially as the amount of trace nitrogen and phosphorus in seawater is increasing. In addition, algae observed in the seas around Belfast and Venice correlated with increased rejection of human waste.

As in document KR20040037467, it has been reported that changing the water temperature may affect the growth of algae. Others have also reported that microorganisms, particularly bacteria, can be used to kill proliferative algae in lakes and rivers (see, for example, KR20180119021). Finally, JPH1171203 disclosed that β-cyano-alanine as an algicide can prove effective in promoting control of blue-green algae in marine environments.

So far, collecting green algae from seawater or shorelines, eg beaches, is the only solution to combat the Ulva lactuka outbreak.

Thus, algae of the genus Ulva , especially the species Ulva lactuca ), there is a need to provide a means to control and/or eradicate the outbreak.

There is also a need to control the generation of Ulva in a safe manner, in particular without the release of toxic acid vapors such as, for example, H ₂ S vapors.

One aspect of the present invention relates to a method for controlling and/or preventing the outbreak of algae in the genus Ulva in a marine environment in need thereof, comprising the step of contacting the marine environment with seawater collected in the Mediterranean Sea. In certain embodiments, the alga of the genus Ulva is an alga of the species Ulva lactuka. In some embodiments, the seawater is at a latitude 43°14'N and a longitude 5°21'E, a latitude 43°09'N and a longitude 5°36'E, a latitude 43°18'N and a longitude 5°17'E, Collected at latitude 43°14'N and longitude 5°17'E, or latitude 43°15'N and longitude 5°19'E. In one embodiment, the seawater is collected at latitude 43°14'N and longitude 5°21'E or latitude 43°09'N and longitude 5°36'E. In certain embodiments, the seawater contains live microorganisms capable of promoting the death of algae of the genus Ulva. In some embodiments, the living microorganism is a virus.

In another aspect, the present invention also provides control of the outbreak of algae in the genus Ulva in a marine environment in need thereof, comprising contacting the marine environment with one or more living microorganism(s) derived from seawater collected in the Mediterranean Sea. and/or to a method for preventing it. In some embodiments, the alga of the genus Ulva is an alga of the species Ulva lactuka. In certain embodiments, the seawater comprises a latitude 43°14'N and a longitude 5°21'E, a latitude 43°09'N and a longitude 5°36'E, a latitude 43°18'N and a longitude 5°17'E, Collected at latitude 43°14'N and longitude 5°17'E, or latitude 43°15'N and longitude 5°19'E. In one embodiment, the seawater is collected at latitude 43°14'N and longitude 5°21'E or latitude 43°09'N and longitude 5°36'E. In some embodiments, the living microorganism is a virus.

Another aspect of the invention relates to the use of one or more living microorganism(s) derived from seawater collected in the Mediterranean Sea for controlling and/or preventing the outbreak of algae in the genus Ulva in a marine environment. In certain embodiments, the alga of the genus Ulva is an alga of the species Ulva lactuka. In some embodiments, the seawater is at a latitude 43°14'N and a longitude 5°21'E, a latitude 43°09'N and a longitude 5°36'E, a latitude 43°18'N and a longitude 5°17'E, Collected at latitude 43°14'N and longitude 5°17'E, or latitude 43°15'N and longitude 5°19'E. In one embodiment, the seawater is collected at latitude 43°14'N and longitude 5°21'E or latitude 43°09'N and longitude 5°36'E. In certain embodiments, the living microorganism is a virus.

Justice

In the present invention, the following terms have the following meanings:

- " about " preceding a numerical value includes up to plus or minus 10% of the numerical value. It should be understood that the value to which the term “about” refers is per se specifically and preferably disclosed.

- " Popogenous " refers to a rapid and excessive increase in a population. Broadly, “ algal versus development ” refers to the rapid and excessive growth of algae in a given marine environment. In fact, algal blooms can be responsible for “ green algae ,” which refers to the green coloration of seawater due to the presence of excessive concentrations of green algae in a given environment. As used herein, " algal bloom " is defined as contaminated water , particularly seawater and shoreline areas, particularly coasts and beaches, as toxic vapors released upon decomposition of algae can be life threatening to both animals and humans. considered a contaminant.

- " Marine environment " refers to ecosystems from seawater, including open sea (or deep sea), coasts, estuaries, and shorelines. In practice, a coastline includes any land or surface in direct contact with the sea, such as rocks and beaches.

- " Controlling " refers to both steps, including prophylactic or preventative steps, undertaken to prevent or slow (mitigate) certain harmful phenomena. Environments requiring this step include not only an environment already experiencing the specific harmful phenomenon, but also an environment prone to experiencing the specific harmful phenomenon or an environment in which the specific harmful phenomenon is to be prevented. The particular noxious event may be determined in accordance with the present invention, after receiving an effective amount of seawater collected from the Mediterranean Sea, the environment may be determined by one or more parameters associated with the specific noxious event; It is successfully “controlled” if it exhibits an observable and/or measurable decrease in or in the absence of a better quality of the environment. The above parameters for evaluating successful control and improvement in the environment can be readily measured by routine procedures familiar to those skilled in the art. In one embodiment, the particular deleterious phenomenon is macroalgae codulation, in particular Ulva lactuca cobiogenesis.

- " Preventing " refers to preventing and/or reducing the likelihood of at least one parameter of a particular harmful phenomenon from occurring.

- " Living microorganism " refers to a microorganism, eg, a protozoa, a bacterium, or a virus, capable of undergoing division within appropriate conditions. In one embodiment, the living microorganism is a virus.

- " Promoting death " refers to the ability to kill a target. By extension, " promoting the death of an algae" is intended to refer to the death or decomposition of algae. In fact, dead algae can no longer grow, spread and promote green algae. In one embodiment, death of the algae may be preceded by efflorescence or bleaching of the algal tissue.

As used herein, the expressions "ulva algae" and "algae of the genus Ulva" are meant to refer to the same subject and are interchangeable.

details

We observed that no major Ulva lactuca outbreaks occurred in the Mediterranean, as observed in the Yellow Sea or Brittany. However, given the presence of Ulva lactuka, a significant lack of tidal water (water stagnation), and the presence of abundant nitrogen and phosphorus sources, an Ulva lactuka outbreak should be expected in the Mediterranean. The inventors surprisingly show that controlling the Ulva lactuca outbreak in Brittany may be feasible by using seawater from one or more selected points of the Mediterranean Sea. More precisely, we provide herein with experimental data showing that seawater contains microorganisms that promote the death of Ulva lactuka and thus control of Ulva lactuka epigenesis, and that these microorganisms are viruses.

One aspect of the present invention relates to a method for controlling and/or preventing the outbreak of algae in the genus Ulva in a marine environment in need thereof, comprising the step of contacting the marine environment with seawater collected in the Mediterranean Sea.

In another aspect, the present invention also relates to the use of seawater collected from the Mediterranean Sea for controlling and/or preventing the outbreak of algae of the genus Ulva in a marine environment in need thereof.

Another aspect of the present invention relates to a method for controlling and/or preventing the outbreak of algae in the genus Ulva in a marine environment, comprising the step of contacting the marine environment with seawater collected from the Mediterranean Sea.

In another aspect, the present invention also relates to the use of seawater collected from the Mediterranean Sea for controlling and/or preventing the outbreak of algae in the genus Ulva in a marine environment.

In certain embodiments, the alga of the genus Ulva are Ulva acantopora ( Ulva acanthophora ), Ulva anandii ( Ulva ) anandii , Ulva Arasakii arasakii ), Ulva armoricana ), Ulva Atroviridis ( Ulva ) atroviridis ), Ulva beytensis , Ulva beyprons ( Ulva ) bifrons ), Ulva brevistipita , Ulva Burmanica ( Ulva ) burmanica ), Ulva californica , Ulva cetomorphoides ( Ulva ) chaetomorphoides ), Ulva clathrate ), Ulva Compressa ( Ulva ) compressa ), Ulva conglobata ( Ulva conglobata ), Ulva cornuta ( Ulva ) cornuta ), Ulva covelongensis , Ulva crassa crassa ), Ulva crassimembrana , Ulva Kurvata ( Ulva ) curvata ), Ulva denticulate , Ulva Diapana ( Ulva ) diaphana ), Ulva Elegance ( Ulva ) elegans ), Ulva enteromorpha , Ulva Erecta erecta , Ulva expansa , Ulva expansa fasciata ), Ulva flexuosa ( Ulva ) flexuosa ), Ulva geminoidea ( Ulva geminoidea ), Ulva gigantea ( Ulva ) gigantea ), Ulva grandis ( Ulva grandis ), Ulva hookeriana ( Ulva ) hookeriana ), Ulva hopkirkii ( Ulva hopkirkii ), Ulva habensis ( Ulva ) howensis ), Ulva Indica ( Ulva ) indica ), Ulva intestinalis ( Ulva intestinalis ), Ulva Intestinaloides ( Ulva ) intestinaloides ), Ulva javanica javanica ), Ulva Killini kylinii ), Ulva lactuca ( Ulva lactuca ), Ulva lactuca ( Ulva ) laetevirens ), Ulva linegii ( Ulva ) laingii ), Ulva Linearless ( Ulva ) linearis ), Ulva Linza ( Ulva ) linza ), Ulva lippii , Ulva Litoralis ( Ulva ) litoralis ), Ulva litorea ( Ulva ) littorea ), Ulva lobate ), Ulva Marginata ( Ulva ) marginata ), Ulva micrococca ( Ulva micrococca ), Ulva mutavilis ( Ulva ) mutabilis ), Ulva neapolitana ( Ulva neapolitana ), Ulva nematoidea ( Ulva ) nematoidea ), Ulva Onoi ( Ulva ) ohnoi ), Ulva Olivasinth ( Ulva ) olivascens ), Ulva Pacifica ( Ulva pacifica ), Ulva papenfussii , Ulva Parva parva ), Ulva Paschima ( Ulva ) paschima ), Ulva Patengensis ( Ulva ) patengensis ), Ulva Perkursa ( Ulva ) percursa , Ulva pertusa , Ulva Philosa phyllosa ), Ulva polyclada, Ulva poppenguinensis ( Ulva ) popenguinensis ), Ulva porrifolia ), Ulva Prosera ( Ulva ) procera ), Ulva Propunda ( Ulva ) profunda ), Ulva prolifera ( Ulva prolifera ), Ulva pseudocurvata ( Ulva ) pseudocurvata ), Ulva pseudolinza ), Ulva Pulchira ( Ulva ) pulchra ), Ulva quilonensis ), Ulva Radiata ( Ulva ) radiata ), Ulva Ralph ralfsii ), Ulva ranunculata ( Ulva ranunculata ), Ulva reticulata ( Ulva ) reticulata ), Ulva rhacodes ), Ulva Rhacodes ( Ulva ) rigida ), Ulva Rotundata ( Ulva ) rotundata ), Ulva Saifulahii ( Ulva ) saifullahii ), Ulva scandinavica ( Ulva scandinavica ), Ulva Serrata ( Ulva ) serrata ), Ulva simplex ( Ulva simplex ), Ulva sorensenii ( Ulva sorensenii ), Ulva spinulosa ( Ulva ) spinulosa ), Ulva stenophylla ), Ulva sublithoralis ( Ulva ) sublittoralis ), Ulva subulata ( Ulva subulata ), Ulva taniata ( Ulva ) taeniata ), Ulva tanneri ( Ulva ) tanneri , Ulva tenera , Ulva torta torta ), Ulva tuberossa ( Ulva ) tuberosa ), Ulva uncialis ( Ulva uncialis ), Ulva uncinate ( Ulva uncinate ), Ulva uncinate ( Ulva uncinate ), Ulva Us neooides ( Ulva ) usneoides ), Ulva utricularis ( Ulva utricularis ), Ulva Utriculosa ( Ulva ) utriculosa ), Ulva uvoides ) and Ulva ventricosa ( Ulva ) ventricosa ) species are selected from the group comprising algae.

In some embodiments, the algae of the genus Ulva are selected from the group comprising algae of the species Ulva armoricana and Ulva lactuka. In one embodiment, the alga of the genus Ulva is an alga of the species Ulva lactuka.

Within the scope of the present invention, algae of the species Ulva lactuka may also refer to enteromorpha algae.

Within the scope of the present invention, "a marine environment in need thereof" refers to a seawater ecosystem that is experiencing or likely to experience an ulva outbreak.

In some embodiments, the marine environment may be limited to seawater, particularly deep seas, coasts, estuaries, and the like.

Indeed, assessing whether a marine environment needs to control and/or prevent the outbreak of algae in the genus Ulva may include one or more of the following parameters, including average seawater salinity, average seawater surface temperature, and average concentration of wolva in the environment. This can be done by measuring

Illustratively, the measurement of the average seawater salinity, that is, the concentration (g) of salt per kg of seawater, may be performed by any method known in the art. Non-limiting examples of suitable methods for measuring seawater salinity include measurement of electrical conductivity (EC), measurement of total dissolved solids (TDS). In some embodiments, a marine environment in which there is a need to control and/or prevent the outbreak of algae in the genus Ulva may have an average salinity comprised of from about 30 g to about 40 g salt per kg of seawater. Within the scope of the present invention, the expression "from about 30 g to about 40 g of salt per kg of seawater" includes 30 g, 31 g, 32 g, 33 g, 34 g, 35 g, 36 g, 37 g, 38 g, 39 g and 40 g of salt per kg seawater. do.

Illustratively, the measurement of the average seawater surface temperature may be performed by any method known in the art. Non-limiting examples of suitable methods for measuring average seawater surface temperature include satellite microwave radiometers, infrared (IR) radiometers, and in situ buoys. In some embodiments, a marine environment in which there is a need to control and/or prevent the outbreak of algae in the genus Ulva may have an average surface temperature comprised between about 12°C and about 25°C, preferably between about 14°C and about 20°C. there is. Within the scope of the present invention, the expression “from about 12° C. to about 25° C.” means 12° C., 13° C., 14° C., 15° C., 16° C., 17° C., 18° C., 19° C., 20° C., 21° C., 22° C. °C, 23 °C, 24 °C and 25 °C.

Illustratively, measurement of the average concentration of algae in the genus Ulva may be performed by any method known in the art. Indeed, the biomass of algae in seawater can be measured by any of the well-established methods, e.g., Hambrook Berkman, J.A. and Canova, M.G. (2007, Algal biomass indicators (ver. 1.0): U.S. Geological Survey Techniques of Water-Resources Investigations, book 9, chap. A7, section 7.4) A non-limiting example of a suitable method for measuring algal biomass is carbon biomass as ash-free dry mass. measurement, measurement of particulate organic carbon (POC), or quantification of chlorophyll a in seawater samples.

In some embodiments, Ulva algal blooms can be controlled in seawater before being stranded, particularly on shorelines, particularly rocks or beaches.

In some other embodiments, Ulva algal blooms can be controlled on any land or surface surface that is in direct contact with the sea, eg, a coastline, including rocks, beaches.

Indeed, the seawater according to the invention can be contacted with algae of the genus Ulva on the shoreline. In some embodiments, the ulva algae are killed prior to their natural biodegradation. Indeed, natural biodegradation begins when significant amounts of toxic acid vapors, especially H ₂ S vapors, are released. Illustratively, once dead, the green algae can be safely removed and/or stored prior to eventual destruction.

In certain embodiments, seawater promotes death of algae of the genus Ulva. In some embodiments, the death of algae of the genus Ulva is achieved without the release of acid vapors, in particular without the release of H ₂ S vapors.

In some embodiments, the seawater is at a latitude 43°14'N and a longitude 5°21'E, a latitude 43°09'N and a longitude 5°36'E, a latitude 43°18'N and a longitude 5°17'E, Collected at latitude 43°14'N and longitude 5°17'E, or latitude 43°15'N and longitude 5°19'E.

In one embodiment, the seawater is collected at latitude 43°14'N and longitude 5°21'E, or latitude 43°09'N and longitude 5°36'E.

In one embodiment, the seawater is collected at latitude 43°14'N and longitude 5°21'E. In one embodiment, the seawater is collected at latitude 43°09'N and longitude 5°36'E. In one embodiment, the seawater is collected at latitude 43°18'N and longitude 5°17'E. In one embodiment, the seawater is collected at latitude 43°14'N and longitude 5°17'E. In one embodiment, the seawater is collected at latitude 43°15'N and longitude 5°19'E.

In practice, seawater can be collected up to a depth of 30 m from the surface. Within the scope of the present invention, the expression "up to 30 m" means 1 cm, 5 cm, 10 cm, 15 cm, 20 cm, 30 cm, 40 cm, 50 cm, 60 cm, 70 cm, 80 cm, 90 cm, 1 m, 1.5 m, 2 m, 2.5 m, 3 m, 3.5m, 4m, 4.5m, 5m, 5.5m, 6m, 6.5m, 7m, 7.5m, 8m, 9m, 10m, 11m, 12m, 13m, 14m, 15m, 16m, 17m, 18m, 19m, 20m, 21m , 22m, 23m, 24m, 25m, 26m, 27m, 28m, 29m and 30m.

In certain embodiments, the seawater is collected at a depth comprised between about 10 cm and about 10 m, preferably between about 50 cm and about 2 m.

In some embodiments, the seawater is collected during the spring season, particularly from March 20 to June 21, and more specifically from May 20 to June 20.

In some embodiments, the collected seawater sample is stored at a temperature of from about 4°C to about 30°C, preferably from about 10°C to about 20°C, more preferably from about 20°C. Within the scope of the present invention, the expression “from about 4° C. to about 30° C.” means 4° C., 5° C., 6° C., 7° C., 8° C., 9° C., 10° C., 11° C., 12° C., 13° C., 14° C. ℃, 15 ℃, 16 ℃, 17 ℃, 18 ℃, 19 ℃, 20 ℃, 21 ℃, 22 ℃, 23 ℃, 24 ℃, 25 ℃, 26 ℃, 27 ℃, 28 ℃, 29 ℃ and 30 ℃ include

Indeed, prior to use to promote the death of algae of the genus Ulva, the collected seawater sample may be preserved for up to 50 days, preferably up to 30 days, more preferably up to 10 days. Within the scope of the present invention the expression "up to 50 days" means 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2 and 1 days.

In certain embodiments, the seawater contains live microorganisms capable of promoting the death of algae of the genus Ulva.

In some embodiments, mortality of algae of the genus Ulva can be assessed by bleaching the green tissue of the algae to white tissue. As used herein, depigmentation of the green tissue of an algae to white tissue may also be referred to as “bleaching” of the green tissue of an algae. Indeed, the observation of dead (necrotic) white tissue can be assessed visually or by light microscopy. In certain embodiments, the white tissue can be observed for about 1 to about 15 days, preferably during the day and/or at a temperature of from about 20°C to about 30°C, after contacting seawater according to the present invention with ulva algae. there is. Within the scope of the present invention, the expression "from about 1 day to about 15 days" means 1 day, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and 15 days. includes Within the scope of the present invention, the expression “from about 20° C. to about 30° C.” means 20° C., 21° C., 22° C., 23° C., 24° C., 25° C., 26° C., 27° C., 28° C., 29° C. and 30° C. ° C.

In practice, the living microorganism is selected from the group consisting of protozoa, bacteria and viruses.

In some embodiments, microorganisms according to the present invention can be enriched, isolated and/or characterized.

In some embodiments, the microorganism according to the present invention can be purified from seawater according to the present invention. As used herein, the term “purified” refers to a step allowing isolation of a microorganism according to the present invention as an active ingredient from other living organisms in seawater according to the present invention. Other living organisms may include algae, phytoplankton, and the like.

Concentration, isolation, and characterization of microorganisms can be performed by any suitable technique state of the art.

In some embodiments, microorganisms can be filtered from the collected seawater sample using, for example, a membrane filter, a Zeitz filter, a sintered glass filter, and/or a candle filter. In practice, the filter may have a pore size ranging from about 0.01 μm to about 10 μm. The expression “from about 0.01 μm to about 10 μm” within the scope of the present invention means 0.01 μm, 0.02 μm, 0.03 μm, 0.04 μm, 0.05 μm, 0.06 μm, 0.07 μm, 0.08 μm, 0.09 μm, 0.1 μm, 0.2 μm. , 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 2 μm, 3 μm, 4 μm, 6 μm, 7 μm, 8 μm, 9 μm, and 10 μm. do.

In some embodiments, the amoeba can be filtered using a filter having a pore size ranging from about 1 μm to about 10 μm. In some embodiments, bacteria can be filtered using a filter having a pore size ranging from about 0.05 μm to about 10 μm, preferably from about 0.1 μm to about 8 μm. In some embodiments, the virus can be filtered using a filter having a pore size ranging from about 0.01 μm to about 1.5 μm, preferably from about 0.1 μm to about 1 μm.

In certain embodiments, the microorganism may optionally be centrifuged by polyethylene glycol (PEG) precipitation followed by differential centrifugation. Reference may be made to the protocol disclosed by Lawrence and Steward (Purification of viruses by centrifugation. 2010; Manual of aquatic viral ecology; Chapter 17, 166-181).

Characterization of microorganisms can be performed by any suitable technique known from the state of the art. Illustratively, next-generation sequencing (NGS) of the entire genome of a microorganism may be performed after extracting nucleic acids from the microorganism. Indeed, viral nucleic acids can be extracted using, for example, the QIAamp viral RNA mini kit (QIAGEN®) or the Pure Link® viral RNA/DNA mini kit (Invitrogen®). Genomic bacterial nucleic acids can be extracted using, for example, the Illustra Bacterial Genome Prep Mini Spin Kit (GE Health Life Sciences®) or the NEBNext® Microbiome DNA Enrichment Kit (New England Biolabs®).

In one embodiment, the living microorganism is a protozoa, in particular an amoeba.

As used herein, the term “protozoa” includes actinopods such as radioworms, sunworms, and acantharia; foraminifera, such as monotalame and polyphthalame; marine protozoa, including amoeba, eg, gymnamoebian, and thecamoevian. Within the scope of the present invention, the expression "marine protozoa" includes marine amoeba.

Non-limiting examples of marine amoeba include genus Clydonella ; genus Lingulamoeba , for example L. Lei ( L. leei ); genus Mayorella , for example M. Gemmifera ( M. gemmifera ); The genus Neoparamoeba , for example N. branchiphila ( N. branchiphila ); genus Vannella , for example V. Aberdonica ( V. aberdonica ), V. Myroides ( V. miroides ); genus Vermistella , for example V. Antarctica ( V. Antarctica ); genus Vexillifera , for example V. Minutissima ( V. minutissima ), V. Including amoeba of Tasmaniana ( V. tasmaniana ).

In one embodiment, the living microorganism is a bacterium, in particular a marine bacterium. Non-limiting examples of marine bacteria include the genus Bacillus , eg, B. Bacillus. Megatherium ( B. megaterium ), B. thuringiensis ( B. thuringiensis ); genus Flavobacterium , for example Formosa agariphila ; genus Halomonas , for example H. Profundus ( H. profundus ), H. hydrothermalis ( H. hydrothermalis ); Pseudomonas genus (genus Pseudomonas ), for example blood. Gezennei ( P. guezennei ); genus Saccharophagus , for example S. Degradans (S. degradans); genus Vibrio , for example V. V. azureus , V. and bacteria of V. proteolyticus .

In one embodiment, the living microorganism is a virus. In certain embodiments, the virus belongs to the family of Mimiviridae . In some embodiments, the virus belonging to the family Mimiviridae is a genus Cafeteriavirus , a genus Klosneuvirus , a genus Mimivirus , a genus Tupanvirus , and the like. In some embodiments, the microorganism is a virus.

In some embodiments, virus from seawater collected from the Mediterranean Sea according to the present invention is filtered through a filter with a pore size of about 0.2 μm. That is, it is understood that the virus passes through a filter with a pore size of about 0.2 μm, which is not retained by the filter.

In a specific embodiment, the presence of viruses in seawater collected from the Mediterranean Sea according to the present invention is dependent on aromatic compounds, particularly SYBR gold dye (N',N'-dimethyl-N-[4-[(E)-(3-methyl-) 1,3-benzothiazol-2-ylidene)methyl]-1-phenylquinolin-1-ium-2-yl]-N-propylpropane-1,3-diamine). SYBR Gold dye preferentially binds to DNA. These dyes are widely used in virology to stain and visualize virus-like particles (VLPs) present in seawater and other aquatic samples.

In some embodiments, the amount of virus in seawater collected from the Mediterranean Sea according to the present invention ranges from about 10 ⁵ to about 10 ⁹ PFU/ml, in particular from about 10 ⁶ to about 10 ⁸ PFU/ml.

As used herein, the expression “from about 10 ⁵ to about 10 ⁹ PFU/ml” means 10 ⁵ , 5×10 ⁵ , 10 ⁶ , 5×10 ⁶ , 10 ⁷ , 5×10 ⁷ , 10 ⁸ , 5 x10 ⁸ and 10 ⁹ PFU/ml.

As used herein, PFU stands for "Plaque Forming Unit" and refers to the number of viral particles capable of forming plaques in a cell monolayer.

Another aspect of the present invention is to control the outbreak of algae in the genus Ulva in a marine environment in need thereof, comprising the step of contacting one or more living microorganism(s) derived from seawater collected in the Mediterranean Sea with the marine environment. / or how to prevent it.

A further aspect of the invention also relates to the use of one or more living microorganism(s) derived from seawater collected in the Mediterranean Sea for controlling and/or preventing the outbreak of algae of the genus Ulva in a marine environment in need thereof. .

In another aspect, the present invention also relates to the use of one or more living microorganism(s) derived from seawater collected in the Mediterranean Sea for controlling and/or preventing the outbreak of algae of the genus Ulva in a marine environment.

In another aspect, the present invention further relates to the use of one or more living microorganism(s) derived from seawater collected from the Mediterranean Sea in a method for controlling and/or preventing the outbreak of algae of the genus Ulva in a marine environment in need thereof. is about

Another aspect of the present invention further relates to the use of one or more living microorganism(s) derived from seawater collected from the Mediterranean Sea in a method for controlling and/or preventing the outbreak of algae of the genus Ulva in a marine environment.

In some embodiments, the effective dose of the virus for controlling and/or preventing the outbreak of algae in the genus Ulva ranges from about 1×10 ¹ to about 1×10 ¹² PFU/m ² of the marine environment being treated. In certain embodiments, an effective dose ranges from about 1×10 ² to 1×10 ⁸ , preferably from about 1×10 ² to about 1×10 ⁸ PFU/m ² of the marine environment being treated.

Within the scope of the present invention, the term "from about 1x10 ¹ to about 1x10 ¹² PFU/m ² of the treated marine environment" refers to 1x10 ¹ , 1x10 ² , 1x10 ³ , 1x10 ⁴ , 1x10 ⁵ , 1x10 ⁶ , 1x10 ⁷ , 1x10 ⁸ , 1x10 ⁹ , 1x10 ¹⁰ , 1x10 ¹¹ and 1x10 ¹² PFU/m ² .

1A-1C are photographs of Enteromorpha algae. 1A : Green tubular algae previously called Enteromorpha collected in November 2018 after an outbreak in the Trieu Fjord (TR) off the north coast of Brittany (48°46'N, 3°06'W). Figure 1b : Tubular disappears after incubation with seawater collected in June 2018 from the Gulf of Marseille (43°18'N 5°16'E or spot X(RS) in Figure 2) for 1 month at 20°C and sun exposure . 1C : “Enteromorpha” became typical Ulva lactuka after 3 months at 20° C. and sun exposure.
FIG. 2 is a schematic showing statistical analysis of British Ulva lactuca proliferation in vitro using a unique sample of seawater from the Gulf of Marseille. Seawater samples collected from three different points in the Gulf of Marseille in June 2018. X(RN) was 43°18'N, 5°16'E; Y(RS) was 43°15'N, 5°19'E, and Z(PR) was 43°14'N, 5°21'E. Seawater samples were divided into three tube groups (n=36). British Ulva Lactuka, collected from Brehec (north coast of Brittany, 48°43'N ² °06'W) in June 2018, cut into 1 cm2 pieces and collected from a point in the Gulf of Marseille one day before sampling (D1) Three groups of tubes corresponding to X, Y and Z were placed. Ulva lactuka propagation was performed at 25° C. with seawater in a 50 ml tube sealed with tape to induce anoxia. Proliferation was observed in 25 tubes/36 (69%) at point X corresponding to the open sea, while 14 tubes/36 (39%) at point Y and 1 tube/36 at point Z closest to the shore. 2.7%) (see inset graph). Confluence was reached after 1 week in tubes where Ulva lactuka was allowed to propagate, and acidity was detected. No acidity was observed in the tube where Ulva Lactuka did not grow, and Ulva Lactuka became white after 5 days. Seawater at point Z was stored from D30 to D180 before reincubation with British Ulva Lactuka, and proliferation was observed at 12 tubes/36 (33%) for D30 and 36 tubes/36 (100%) for D180. (see inset graph).
3A-3D are photographs showing comparison with light microscopy of Ulva lactuka in three different states. 3A : Ulva lactuka became white in 5 days when incubated with seawater from the Z point of the Gulf of Marseille at 20° C. and sun exposure. 3B : Light microscopy (10X) of white Ulva lactuka. Ulva lactuka tissue remains unaffected by the regular tissue of Ulva cells. 3C : Light microscopy (10X) of healthy Ulva lactuka. 3D : Light microscopy (10X) of Ulva lactuka after acidic biodegradation. Ulva lactuka tissue is destroyed by the release of chlorophyll, which remains green despite anoxia. Taken with a Nikon D3100 camera connected to a Nikon Eclipse Ti L100 microscope (Nikon, Tokyo, Japan).
4A-4D are photographs and graphs showing fluorescence microscopy after SYBR staining. Figure 4a-c : Seawater from the Mediterranean that induces bleaching was cultured without Ulva (Panel A) and with Ulva (Panels B and C). Figure 4D : depicts the amount of virus-like particles expressed in number of particles/ml. The seawater was filtered to 0.2 μm.

Example

The invention is further illustrated by the following examples.

Example : Ulva lactuca Identification of seawater samples that promote death

1) Materials and methods

a) Ulva Lactuka polymorphism

Green algae were collected from the Trieu fjord on the northern coast of Brittany (48°46'N, 3°06'W). Propagation was performed in vitro using seawater samples from the Gulf of Marseille (Provence, southern France). A green tubular algae, previously termed enteromorpha, was collected in November 2018 after an outbreak in the Trieu fjord on the north coast of Brittany (48°46'N, 3°06'W). Cultivation was performed for one month with seawater collected in June 2018 from the northern bay of Marseille (43°18'N, 5°16'E; RN) at 20°C and sun exposure.

b) Ulva Lactuka multiplication

Seawater samples were collected in spring (2018, 2019, June 2020) from eight different points, including three different points in Marseille ( Figure 2 ), two points in Provence, and three points in Brittany (see Table 1 ). ) were collected from the indicator. Seawater samples were divided into three groups of tubes (n=36). British Ulva Lactuka, collected from Brehec (north coast of Brittany, 48°43'N ² °6'O) in June 2018, cut into 1 cm2 pieces, and collected from a point in the Gulf of Marseille one day before sampling (D1) Three groups of corresponding X, Y and Z were placed in falcon tubes (50 ml). Acidity was tested with a Cresson pH meter (Barcelona, Catalonia). The pH meter was calibrated prior to any measurements. Nitrate was measured with a METRHOM chromatography ion apparatus (Bern, Switzerland) equipped with a Metrosep column A supp 5 150/4 mm using 3.2 mM Na ₂ CO ₃ /1 mM NaHCO ₃ as an eluent. The seawater was diluted 1/8 and the standard was used to correct the amount of nitrate.

c) light microscopy

Light microscopy (10X) was performed using water samples collected at the Z(PR) point in the Bay of Marseilles before confluence, in healthy Ulva lactuka after acidic biodegradation, and in white Ulva lactuka 5 days later. Photography was performed using a camera Nikon D3100 connected to a Nikon Eclipse Ti L100 microscope (Nikon, Tokyo, Japan).

d) Diode Array Detection High Performance Liquid Chromatography (DAD) HPLC )

Seawater samples were filtered to 0.2 μm and analyzed with a Beckman HPLC System Gold instrument equipped with a reverse phase (C8) column using H ₂ O 0.1% TFA (A) and CH ₃ CN 0.1% TFA (B). The gradient was 10% to 50% B at 40 min, 10 min at 90% B and 10 min at 10% B. A diode array detector Beckman device was coupled behind the injector. The flow rate was 0.8 ml/min.

e) SYBR Fluorescence microscopy after staining

Mediterranean seawater with or without Ulva lactuka samples was filtered through a 0.22 μm membrane filter (Millex®; catalog number SLGP033RS) to remove cells, followed by a 0.02 μm bipolar filter (Whitman®; catalog number) using a vacuum filtration system. Virus particles were collected by filtration through WHA68096002).

The filter was then filtered with SYBR Gold dye (N',N'-dimethyl-N-[4-[(E)-(3-) Stained with methyl-1,3-benzothiazol-2-ylidene)methyl]-1-phenylquinolin-1-ium-2-yl]-N-propylpropane-1,3-diamine) and sterilized in 500 μL Washed 3 times with 0.02 μm-filtered mQ water. Stained virus-like particles were observed with an epifluorescence microscope Leica SP2.

2) Results

a) britain Ulva Lactuka is Can grow in the Mediterranean Sea and has a different phenotype with respect to salinity

Ulva Lactuca lives naturally in the Gulf of Marseille (Provence, southern France) and appears every winter. Ulva grows rapidly from February to March and then disappears rapidly in spring. As observed in Brittany, no Ulva lactuka outbreaks have been reported in the Gulf of Marseille, which is high in phosphate and nitrogen and has shallow beaches. The first hypothesis may be that British Ulva lactuka can grow readily in Brittany but not in the Mediterranean Sea, and more particularly that the nitrate concentration is lower in Brittany's seawater. Five points near Marseille were selected, seawater samples were collected and compared to three points in Brittany ( Table 1 ).

[Table 1]

^* Statistical analysis of British Ulva bleaching in vitro using seawater samples collected in spring. All experiments (n = 8) were performed in 2018, 2019 and 2020 with British ulva collected from the Trieu Fjord (TR) in northern Brittany. Ulva was cut into pieces of 1 cm ² , placed in seawater (40 ml) in a tape-sealed tube (n = 25), and left in sunlight at an average temperature of 25° C.

The Gulf of Marseille is located at a distance of 20 km from the mouth of the Rhône River and is dominated by northwest winds (Mistral and Tramontan) that regularly blow from the Rhône into Marseille. Table 1 shows that pH and conductivity measurements (mainly related to salinity) are low at RN, probably due to the influence of the Rhone River. Table 1 shows that the concentrations of nitrates in coastal waters are equivalent in Brittany (BR and PO) and Provence (RN, WF, RS). However, nitrate concentrations can be much higher in the Brittany Fjords (TR) or in the Calanques (MU) and Marina (PR) of Provence.

As indicated above, British Ulva Lactuka can grow rapidly in the seawater of Marseille ( FIG. 1 ). The polymorphism of Ulva lactuca, previously termed enteromorpha, was collected from the Trieu fjord near the city of Fengfol (northern Brittany), which became a typical Ulva lactuka after 3 months at 20 °C ± 10 °C and sun exposure ( Figure 1c ). was tested with green tubular algae ( FIG. 1A ). This experiment shows the importance of salinity in the polymorphism of Ulva lactuka as previously described (Rybak, Ecological Indicators, 2018, 85, 253-261).

b) Britain Ulva Lactuka The breeding differs in the location and timing of water sampling in the Gulf of Marseille.

Natural biodegradation on the beach occurs when Ulva lactuka reaches a confluence that causes anoxia characterized by H ₂ S production. In the case of this biodegradation, Ulva may turn white due to dehydration. However, this is another phenomenon we observed in Ulva Lactuka, Britain in seawater collected from Marseille. The British Ulva Lactuka quickly turned white (bleached) in one day without dehydration. To simulate this natural process, the propagation of Ulva lactuka was performed using seawater in a 50 ml tube sealed with tape to induce anoxia.

Statistical analyzes were performed using seawater samples collected from three different points in Brittany, including the Gulf of Marseille, and five points in Provence ( Table 1 and Figure 2 ). Seawater samples were divided into 8 groups of tubes (n=36). British Ulva lactuka was cut into pieces of 1 cm ² , and points X(RN), Y(RS) and Z(PR) in the Gulf of Marseille collected one day before sampling (D1), PR and MU, TR and BR in Provence ( 8 groups of tubes corresponding to northern Bretagne) and PO (South Brittany).

No bleaching was observed with seawater collected from Brittany during the springtime when Ulva growth was highest. For the five different points in Provence, the number of tubes in which propagation could occur was not the same. Proliferation was only observed in 25 tubes/36 (69%) for point X corresponding to the open sea, 14 tubes/36 for point Y, and 1 tube/36 for point Z closest to shore. As shown in FIG. 3A , Ulva lactuka could not grow in the tube, and Ulva lactuka became white under sunlight at 20° C. within 5 days with no detectable acidity. This ulva lactuka white phenotype was not similar to the white dehydrated wolver lactuka observed in Brittany when Ulbu lactuka stayed ashore at low tide. For tubes in which Ulva-lactuca can proliferate, confluence was reached after 1 week, and acidity was observed following the regular course of Ulva-lactuca biodegradation (Dominguez and Loret, Mar Drugs. 2019 Jun 14;17 (6). ).Pii: E357). As observed in natural conditions, Ulva lactuka remained green under biodegradation. Seawater from point Z ( FIG. 2 ) was maintained from D30 to D180 before being re-incubated with British Ulva Lactuka, and proliferation was observed at 12 tubes/36 for D30 and 36 tubes/36 for D180. became ( FIG. 2 ). The active ingredient that promotes the death of British Ulva lactuka cells is not a contaminant that would have produced the same effect from D1 to D180. Other British algae (mainly brown) were not affected by seawater from the Gulf of Marseille (data not shown).

c) three different states Ulva lactuca Comparison with light microscopy showed that the tissue was white Ulva lactucaro not to be destroyed show

What happens in FIG. 3A showing white Ulva lactuka was studied at the tissue level using light microscopy. Figure 3b shows that the white tissue of Ulva lactuka is in the regular organization of Ulva lactuka cells comparable to healthy Ulva lactuka with a frond composed of hard cells with chlorophyll present in the cytoplasm that gives the cells a green color ( Figure 3c ). It shows that it remains unaffected. Although the white color in Figure 3b indicates that the cells have died, this death is not due to macro predators or environmental conditions that can destroy the tissue tissue of the algal tissue as shown in Figure 3c. This is not sporulation that can give it a white color. The main explanation from these preliminary experiments is that micro-organisms specific to Ulva-lactuca control the Ulva-lactuca outbreak in the Mediterranean. Only microbial attack, particularly viral attack, could explain this rapid death of Ulva lactuka cells without tissue damage. Also, this hypothesis was confirmed. In fact, when seawater is filtered at 0.2 μm, Ulva lactuka can still turn white, showing that the bleaching activity is not due to plankton, amoeba or bacteria having a size greater than 0.2 μm.

d) for high performance liquid chromatography combined Diode Array Detection (DAD) HPLC )

The bleaching-induced Mediterranean seawater was filtered to 0.2 μm and then analyzed by DAD HPLC allowing analysis of the UV spectrum of each body eluting at different times from a hydrophobic C8 column with an acetonitrile gradient. Most of the peaks eluting between 5 and 45 min are characterized by a UV spectral signature showing an absorption maximum at 243 nm and correspond to organic macromolecules called colloids. A 3D view of the DAD HPLC run shows that colloids are a major component of seawater filtered at 0.2 μm. The three peaks have different UV spectral signatures. The peak indicated by the red arrow at 3.5 min may correspond to the presence of viral particles and is characterized by a first maximum absorbance at 266 nm due to nucleic acids and aromatic amino acids. The two other peaks correspond to 6 min of free nucleic acid and 45 min of free protein, characterized by absorbance maxima at 260 and 280 nm, respectively. When British Ulva Lactuka is added to Mediterranean seawater for 5 days and when bleaching occurs, the peak corresponding to the virus increases significantly at 266 nm with a maximum absorbance ranging from 7 to 32 mAU. Interestingly, this peak, compatible with viral particles, increases by 78%, while the colloidal peak decreases (probably due to Ulva uptake).

e) virus-like particle staining and fluorescence microscopy

Mediterranean seawater without or containing Ulva lactuka was filtered to 0.2 μm, and then SYBR gold dye (N',N'-dimethyl-N-[4-[(E)-(3) Aromatics termed -methyl-1,3-benzothiazol-2-ylidene)methyl]-1-phenylquinolin-1-ium-2-yl]-N-propylpropane-1,3-diamine) dyed with the compound. These dyes are widely used in virology to stain and visualize virus-like particles (VLPs) present in seawater and other aquatic samples. There are hundreds of published reports for counting and detecting viruses in biological samples using this methodology (Shibata et al., Aquat Microb Ecol. 2006, 43, 223-231). 4a-c show that fluorescence microscopy after SYBR staining indicates high virus production when Ulva lactuka is added to seawater. This high virus production is already important when Ulva lactuka is still green. However, when Ulva lactuka becomes white, the virus abundance reaches 6.5×10 ⁸ virus/ml, which is a high concentration of atypical virus ( FIG. 4d ). These experiments suggest that the virus is actively produced and that Ulva lactuka is released at a higher rate when bleached.

3) discussion

The average nitrate concentration in seawater and the Mediterranean Sea around the world is about 1 μM. When nitrate concentrations were the reason for the absence of Ulva lactuca growth in Marseille, nitrate concentrations of up to 100 μM could be expected on the northern coast of Brittany, where algae was most important in Western Europe, especially in springtime, but not in rivers or fjords ( Table 1 ). Nitrate concentrations vary according to the season. On the northern coast of Brittany there was an average of 5 μM at the Roscoff marine station, almost 10 μM in winter 2018 and 2019 and 1 μM in summer (see: Service d'Observation en Milieu Littoral (SOMLIT), INSU-CNRS, Roscoff and Marseille") http://somlit-db.epoc.u-bordeaux1.fr/bdd.php Other parameters such as pH and conductivity measurements also vary depending on the season of the roscope (see http://somlit-db. epoc.u-bordeaux1.fr/bdd.php) Data from BR off the north coast of Britain ( Table 1 ) are within the range of nitrate concentrations observed in Roscoff, with the same seasonal variability observed in Marseille (http://www.bdd.php). ://somlit-db.epoc.u-bordeaux1.fr/bdd.php) This seasonal variability was also observed in Galicia, western Spain (Villares et al., Bol. Inst. Esp. Oceanogr. 1999, 15). , 337-341).It is also important to point out that the origin of the Ulva algae does not necessarily come from the coast of Brittany.Ulva breeding is observed in the central North Atlantic, where Ulva drifts to Brittany due to the prevailing westerly winds in the North Atlantic. appears to occur more and more frequently in the North Atlantic, and the main cause of algal blooms may be mainly due to global warming.The ongoing investigation of nitrate concentrations compared with the same objective analysis method, nitrate concentrations in Marseille compared to the northern coast of Britain This was not done because it was intended to explain the absence of Ulva proliferation only in the spring, which could be much lower. This turned out not to be the case, and according to very interesting surveys conducted in the Gulf of Marseille by IFREMER in 2007 and 2008, nitrate concentrations may be as high as in the open sea near Marseille on the coast of northern Brittany with nitrate concentrations above 8 μM measured three times in June 2008 (See Young et al., PLoS One. 2016, 11(5):e0155152). In addition, chlorophyll activity appears to be abnormally low with respect to nutrient concentration (0.2 μg/ml) and can grow up to 1 μg/ml for a very short period that can be explained by viral lysis that regulates proliferation (Young et al. ., PLOS One. 2016, 11(5):e0155152).

Viruses are well known to participate in the control of microalgal blooms, but this has so far not been demonstrated for macroalgae. Viral control of microalgal blooms has resulted in two microalgae, Aureococcus Aureococcus , which cause harmful macroalgae off the east coast. anophagefferens ) (Moniruzzaman et al., Front Microbiol. 2018, 9,752-758) or Tetraselmis from Hawaii ( Schvarcz and Steward, Virology 2018, 518,423-433) were recently observed in the United States. In both cases, it was due to a recently discovered virus called giant virus. Giant viruses were first discovered in amoeba (La Scola et al., Science 2003, 299, 2033-2038). It is interesting that a moving amoeba was detected in the microscope of Fig. 3b . The size of most viruses known after a century is less than 400 nm, for example, 160 nm for HIV and 20 nm for the smallest viruses (Parvoviruses infected pigs), but the size of giant viruses is up to 1 μm. Since then, giant viruses have all been discovered worldwide, infecting many species, particularly marine species (Abergel et al., FEMS Microbiol Rev 2015, 39,779-796).

The Ulva Lactuka Outbreak will remain the cause of a problem that can grow with global warming. However, there is a natural law hypothesis of "Kill the Winner" that could hamper this Ulva Lactuka success story. When there is proliferation of a species, the predator of this species appears to control this proliferation. The largest of the most powerful natural predators are not necessarily the most efficient. The appearance of specific predators of Ulva lactuka may be the result of high concentrations of predators in the Mediterranean such as viruses, marine bacteria and amoeba. Viruses are the most abundant organisms in seawater that can be found even in the lunch sea (1,000 to 2,000 m) region, and the Mediterranean Sea appears to have the highest concentration mainly in the surface water layer (5 m) region. When prokaryotes and unicellular algae appear to be the major viral hosts, only 9% of the sequences obtained from the viral fraction have an identifiable viral origin and no studies have been conducted with sequences specific for giant viruses. Predator dynamics may differ with respect to temperature, which may explain why Ulva lactuka disappears from the Gulf of Marseille in spring when temperatures reach 15°C.

The experiments described for the present invention demonstrate that water samples from the Gulf of Marseille can be used to control British Ulva Lactuca growth. This control is achieved by the microscopic live active ingredient, the concentration of which is not the same for the different points in the Gulf of Marseille. Importantly, sample collections in the spring (2018, 2019, 2020) for three consecutive years (2018, 2019, 2020) from the same point (PR) in the Gulf of Marseille were all able to achieve Ulva lactuka bleaching, which means that microorganisms, especially viruses, are continuously recovered from this marine environment. indicates that it has been

Claims (16)

Controlling the bloom of alga of the genus Ulva in a marine environment in need thereof, comprising the step of contacting the marine environment in need thereof with seawater collected from the Mediterranean Sea and/or a method for preventing. The method according to claim 1, wherein the alga of the genus Ulva is an alga of the species Ulva lactuca . 3. The method of claim 1 or 2, wherein said seawater is at latitude 43°14'N and longitude 5°21'E, latitude 43°09'N and longitude 5°36'E, latitude 43°18'N and longitude 5 Method, collected at °17'E, latitude 43°14'N and longitude 5°17'E, or latitude 43°15'N and longitude 5°19'E. 4. The method according to any one of claims 1 to 3, wherein the seawater is collected at latitude 43°14'N and longitude 5°21'E, or latitude 43°09'N and longitude 5°36'E. . 5. The method according to any one of claims 1 to 4, wherein the seawater comprises live microorganisms capable of promoting the death of algae of the genus Ulva. 6. The method of claim 5, wherein the living microorganism is a virus. Controlling and/or preventing the outbreak of algae in the genus Ulva in a marine environment in need thereof, comprising contacting the marine environment in need thereof with one or more living microorganism(s) derived from seawater collected in the Mediterranean Sea. way for. The method according to claim 7, wherein the alga of the genus Ulva is an alga of the species Ulva lactuca. 9. The seawater according to claim 7 or 8, wherein said sea water is at latitude 43°14'N and longitude 5°21'E, latitude 43°09'N and longitude 5°36'E, latitude 43°18'N and longitude 5 Method, collected at °17'E, latitude 43°14'N and longitude 5°17'E, or latitude 43°15'N and longitude 5°19'E. 10. The method according to any one of claims 7 to 9, wherein the seawater is collected at latitude 43°14'N and longitude 5°21'E, or latitude 43°09'N and longitude 5°36'E. . 11. The method according to any one of claims 7 to 10, wherein the living microorganism is a virus. Use of one or more living microorganism(s) derived from seawater collected in the Mediterranean Sea for controlling and/or preventing the outbreak of algae in the genus Ulva in a marine environment. 13. Use according to claim 12, wherein the alga of the genus Ulva is an alga of the species Ulva lactuka. 14. The method of claim 12 or 13, wherein said seawater is at latitude 43°14'N and longitude 5°21'E, latitude 43°09'N and longitude 5°36'E, latitude 43°18'N and longitude 5 Use, collected at °17'E, latitude 43°14'N and longitude 5°17'E, or latitude 43°15'N and longitude 5°19'E. 15. Use according to any one of claims 12 to 14, wherein the seawater is collected at latitude 43°14'N and longitude 5°21'E, or latitude 43°09'N and longitude 5°36'E. . 16. The use according to any one of claims 12 to 15, wherein the living microorganism is a virus.

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